This comprehensive and rigorous educational text is dedicated to the study and application of the fundamentals of quantitative chemistry. Through sixty clearly and precisely solved exercises, it addresses essential topics such as: molar mass and molecular weight, the concept of the mole, Avogadro's number, the calculation of atoms and molecules in known quantities, percent composition of compounds, determination of empirical and molecular formulas, and the balancing of chemical equations. It serves as an effective tool for chemistry students and for anyone wishing to deepen their understanding of the discipline through a practical and methodical approach, providing solid skills that are essential for continuing in scientific studies.